TITLE: GCN CIRCULAR NUMBER: 32470 SUBJECT: GRB 220813A: Swift/UVOT Detection DATE: 22/08/14 09:55:19 GMT FROM: Paul Kuin at MSSL npkuin@gmail.com
N. P. M. Kuin (UCL-MSSL) and M. G. Bernardini (INAF-OAB) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 220813A 100 s after the BAT trigger (Bernardini et al., GCN Circ. 32465). A source consistent with the XRT position (Osborne et al., GCN Circ. 32466) is detected in the initial UVOT exposures.
The preliminary UVOT position is: RA (J2000) = 05:26:07.60 = 81.53166 (deg.) Dec (J2000) = -33:00:59.0 = -33.01638 (deg.) with an estimated uncertainty of 0.52 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 100 250 147 19.67 +/- 0.11 v 589 1581 117 >18.3 b 515 1506 97 >19.6 u 258 1652 360 >20.6 w1 638 1630 117 >19.6 m2 613 1605 117 >20.1 w2 564 1556 117 >20.0
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.022 in the direction of the burst (Schlegel et al. 1998).